3-Tier Dependent Drop Boxes

I'm using Excel 2010 to try and simplify a script breakdown template for an effects house. The idea is that a coordinator for a show could quickly and easily populate a list of tools/resources needed for a scene by selecting from a group of 3 drop boxes. Here's what i'm looking to accomplish:

- Box 1 would select the "Category"
- Based on Selection in Box #1, Box #2 would present the "Classes" available within the category
- Based on the selections in Box #1 & #2, Box #3 would list all equipment available within that class
- Boxes #2 and #3 should reset if a change is made in the selection in the previous box**
- Rental price for each item displayed at top of each column

I've been able to get the boxes #2 and #3 displaying the right text, and using a VLOOKUP function i have been able to get the rental price of the item to display above the drop down menus, HOWEVER i have not been able to get boxes #2 and #3 to reset if the box above them is changed. Is there any advice on how to do this?

Sample worksheet attached.